Photographic developing-paper.



110.758,312.' A PATBNTED APR. 26', 1904.

- P. GNTHER;

PHOTOGRAPHIG DEVELOPING PAPER.

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UNITED STATES Patented April 2e, 1904.

PATENT OFFICE.

FRITZ GUNTHEROF BERLIN, GERMANY, ASSIGNOR TO OHEMISOHE FABRIK ,AUF AOTIEN, (VORM. SOHERING,) OF BERLIN, GERMANY.

PHOTOGRAPHIC DEvELoPlNG-PAPER.

SPECIFICATION forming part of Letters Patent No. 758,312, dated April 26, 1904.

Application tiled October 31', 1903. Serial No. 179,377. (No specimens.)

To all whom, t Wawy concern:

Beit known that I, FRITZ GNTHER, chemist, doctor of philosophy, a subject oi' the Emperor of Germany, residing at Berlin, Kingdom of Prussia, German Empire, have invented a new and useful Improvement in Photographic Developing Papers, of which the following is a specilication.

It has before been proposed to provide photographic printing-paper-such as chlorid-otsilvercollodion paper, albumen-paper, and the likewith a permanent coating of gelatin for the purpose of protecting the finished picture in such manner as to render it indestructible 'and similar to a gelatin-print.

The present invention has, on the contrary,

for its object to produce improved photographic so-called developing-papers the emulsion layer of which is protected up to the time it comes to be used in photographic baths against friction, pressure, and other mechanical influences in such manner that the well-known unpleasant clouded, covered, or veiled eiect, which can be removed from the finished print only with great diiculty, no longer appears. This unpleasant effect, which does not arise in .the ordinary printing-papers, is avoided according to this invention by providing the sensitized layer of developingpaper with an indilerent transparent layer which becomes dissolved in the photographic bath, so that the finished picture does not contain any coating.

The character of the tin- Y ished picture is therefore not affected by this removable or soluble coating. Such a coating can be advantageously produced by means of dextrose.

In case of bromid-o-silver-gelatin paper the process is, .for instance, as follows: The sensitized layer is coated with a ve-per-cent. solution of dextrose, which on drying leaves behind a coating of dextrose on the sensitized paper. DeXtrose can of course be replaced by other suitable substances easily soluble in water-for inst-ance, dextrin or gum-arabic.

The accompanying drawing represents, on a greatly-enlarged scale, a cross-section of a sheet of my improved photographic developing-paper@ representing the paper, t the photosensitive layer 0r iilm, and c the soluble protective coating.

I claim as my invention Photographic developing paper provided with a photosensitive layer and with a protective transparent and soluble coating for said layer, which coating is adapted to be dissolved and removed from the photosensitive layer in the photographic bath.

In testimony whereoil I have signed my name to this specification in the presence of two subscribing witnesses.

FRITZ GNTHER.

Witnesses:

HENRY HAsrER, Y IVOLDEMAR HAUPT. 

